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-rw-r--r--crypto/sha3/shake.go60
1 files changed, 60 insertions, 0 deletions
diff --git a/crypto/sha3/shake.go b/crypto/sha3/shake.go
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+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha3
+
+// This file defines the ShakeHash interface, and provides
+// functions for creating SHAKE instances, as well as utility
+// functions for hashing bytes to arbitrary-length output.
+
+import (
+ "io"
+)
+
+// ShakeHash defines the interface to hash functions that
+// support arbitrary-length output.
+type ShakeHash interface {
+ // Write absorbs more data into the hash's state. It panics if input is
+ // written to it after output has been read from it.
+ io.Writer
+
+ // Read reads more output from the hash; reading affects the hash's
+ // state. (ShakeHash.Read is thus very different from Hash.Sum)
+ // It never returns an error.
+ io.Reader
+
+ // Clone returns a copy of the ShakeHash in its current state.
+ Clone() ShakeHash
+
+ // Reset resets the ShakeHash to its initial state.
+ Reset()
+}
+
+func (d *state) Clone() ShakeHash {
+ return d.clone()
+}
+
+// NewShake128 creates a new SHAKE128 variable-output-length ShakeHash.
+// Its generic security strength is 128 bits against all attacks if at
+// least 32 bytes of its output are used.
+func NewShake128() ShakeHash { return &state{rate: 168, dsbyte: 0x1f} }
+
+// NewShake256 creates a new SHAKE128 variable-output-length ShakeHash.
+// Its generic security strength is 256 bits against all attacks if
+// at least 64 bytes of its output are used.
+func NewShake256() ShakeHash { return &state{rate: 136, dsbyte: 0x1f} }
+
+// ShakeSum128 writes an arbitrary-length digest of data into hash.
+func ShakeSum128(hash, data []byte) {
+ h := NewShake128()
+ h.Write(data)
+ h.Read(hash)
+}
+
+// ShakeSum256 writes an arbitrary-length digest of data into hash.
+func ShakeSum256(hash, data []byte) {
+ h := NewShake256()
+ h.Write(data)
+ h.Read(hash)
+}